ChargeOver - ChargeOver automates recurring billing, subscription billing, & payment acceptance. A SaaS that integrates with Xero, Quickbooks, & has an API. Free trial.
Squarify.io - Sync inventory between Square and Shopify.
MinuteDock - Web-based time tracking software designed to integrate with the Xero accounting package.
Bonsai Payments - Simple invoicing & payments for small businesses and freelancers. Collect instant payments or set up recurring payments. Get paid via credit card or bank deposit in 100+ currencies.
fusebill - Fusebill is the leading recurring billing and subscription management software for businesses. Try Fusebill for subscription billing made easy!
Shopify Tap & Chip Reader - Mobile POS hardware that connects to the rest of Shopify